Kent Marine Reef Starter Kit provides quality products for the three most important additives for marine invertebrate keeping: calcium, strontium, and iodine. Contains 4 oz bottle of each: Liquid Calcium - provides bio-available calcium for healthier, more beautiful corals; Strontium & Molybdenum - corals will open more and stay attached to their skeletons better; Iodine - provides for proper growth of invertebrates and algae. Each supplement only requires 1 tsp. per 50 gallons. Shipping weight: 1 1/4 lbs.